Mesoblastic nephroma contains fibronectin but lacks laminin.

Non-metastatic mesoblastic nephromas from four young children were shown to contain fibronectin but not laminin using an immunoperoxidase staining procedure. In contrast, one metastasising spindle celled sarcomatous tumour from a neonate was laminin positive. During embryogenesis primitive nephrogenic mesenchyme contains only fibronectin and no laminin; metanephric blastema (permanent kidney) is positive for laminin. The staining for fibronectin and laminin may help to ascertain the histogenesis of different types of renal tumour.